Integrated circuit configuration

ABSTRACT

An integrated circuit containing a plurality of data processing circuit elements  4, 6, 8, 10, 12, 14  and  16  is provided with a configuration data memory  12 . Upon initialisation of the integrated circuit  2 , configuration data is read from the configuration data memory  12  and used to set up configuration program software  26  that controls the interaction between application program software  18, 20, 22  and the integrated circuit  2 . The configuration data is automatically formed from a human readable hierarchical description of the integrated circuit  2  in the form of an ASN.1 description.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to integrated circuits. More particularly, this invention relates to integrated circuits including a plurality of data processing circuit elements having a variable configuration.

[0003] 2. Description of the Prior Art

[0004] The trend towards higher levels of integration within data processing systems has led to many more data processing circuit elements being included on a single integrated circuit. For example, so called system-on-a-chip integrated circuits may typically include a processor core, on-chip memory, several peripheral devices, timers and the like such that few additional components are required outside of the integrated circuit to make a functioning device. It will be appreciated that there are many possibilities for different data processing circuit elements that may be included within a single integrated circuit and that these data processing data elements may be configured in a variety of different manners to suit the particular device being produced.

[0005] At the same time as the trend towards system-on-a-chip designs, there is also a strong desire to reduce the development time for new devices. A significant amount of time in the development of a new device may be expended in writing and testing software, such as, for example, BIOS software, that controls the low-level interaction between the various hardware elements with the specific parameters of a particular system-on-a-chip design. It will be further appreciated that if a mistake is made in the way in which an integrated circuit is configured for manufacture, then this can be extremely expensive to rectify.

SUMMARY OF THE INVENTION

[0006] Viewed from one aspect the present invention provides an integrated circuit comprising:

[0007] (i) a plurality of data processing circuit elements;

[0008] (ii) a configuration memory storing configuration data describing said plurality of data processing elements; and

[0009] (iii) configuration logic operable upon initialisation of said apparatus to read said configuration data from said configuration memory and to determine therefrom configuration parameters of said integrated circuit for setting up configuration program software controlling interaction between application program software and said plurality of data processing circuit elements.

[0010] The invention recognises that there are considerable advantages to be gained by storing configuration data within the integrated circuit hardware itself and having the system use this data to set up the interaction between the hardware and application software when the integrated circuit is initialised. The configuration program software, such as BIOS software, can be generic over a wide variety of integrated circuit devices whilst setting up the particular configuration of a device upon which it is to operate from the configuration memory of that device. This considerably reduces the development and testing time needed for the configuration program software to be used on each device and allows changes to be made to the configuration of the device in a much more straightforward manner.

[0011] It will be appreciated that the provision of the configuration memory within the integrated circuit runs counter to the technical prejudice within the integrated circuit field of reducing the circuit element and gate count of an integrated circuit as much as possible. However, the advantages of the present invention more than justify the increased gate count of providing such an on-chip configuration memory.

[0012] It will be appreciated that the divisions between the functionality provided by different software elements in a system are often not clear cut, but in many preferred embodiments of the invention the configuration program software is basic input/output system software.

[0013] Many system-on-a-chip devices include a processor core responsive to program instructions. Such devices have a high degree of flexibility in the operations they perform. Within such systems the configuration logic operable upon initialisation can be provided in the form of the processor core operating the control of initialisation program instructions. Whilst this may in practice be the most likely way in which the configuration logic is embodied, it would also be possible to provide special purpose hardware to form the configuration logic.

[0014] It will be appreciated that the configuration data can take a very wide range of forms and include a wide range of levels of detail. However, particularly preferred data useful in establishing the operation of the integrated circuit is as follows:

[0015] Data identifying a processor core

[0016] Data identifying type, manufacturer or variant of a system component

[0017] Data controlling a Memory Management Unit

[0018] Data identifying a type of data memory present

[0019] A capacity value of a data memory present

[0020] A page size of a data memory present

[0021] Access parameters for all or parts of a data memory present

[0022] A memory address associated with a data processing peripheral circuit

[0023] An interrupt associated with a data processing peripheral circuit

[0024] An indication of whether a library of software of routines is present, and

[0025] Data heap configuration data for such software routines

[0026] The configuration memory could take a variety of forms. It could take the form of embedded special purpose circuit elements that may be read under software control. However, the configuration memory is preferably provided in the form of a more generic read only memory in which the configuration data is fixed at manufacture. Such an arrangement allows the configuration data to be more easily changed relatively late in the design of an integrated circuit.

[0027] In order to protect proprietary information regarding how a particular device is configured, it may be preferred that the configuration data is encrypted.

[0028] A further problem in developing system-on-a-chip designs is that individual minor variants of the configuration of the system can require considerable effort to be expended in modifying the software that will control that system. Furthermore, there are many different ways in which a highly integrated system may be documented and described which has the result that re-use of previously generated designs is made more difficult.

[0029] Viewed from another aspect the present invention claims a method of describing an integrated circuit having a plurality of circuit elements and associated configuration parameters, said method comprising the step of:

[0030] (i) generating a description of said integrated circuit using a predetermined hierarchical syntax to form a human readable hierarchical description.

[0031] The present invention recognises that by applying a rigorous methodology to the way in which an integrated circuit is described significant advantages may be realised. A human readable description formed in accordance with a predetermined hierarchical syntax allows the possibility for subsequent machine interpretation of that written description in a manner that may be used to automatically generate data or software for controlling the system. Thus, minor configuration changes may be made in the human readable description and these changes automatically interpreted (in a process analogous to program compilation) to form configuration data or controlling software for the system. In addition, the predetermined hierarchical syntax in which the integrated circuit is described makes the re-use of previously generated designs easier since another designer may more readily understand and appreciate the level of detail they require within a particular pre-existing design without having to search through a description in a individual form produced by a particular author.

[0032] It will be appreciated that the hierarchical form allows the possibility for multiple levels within the description with one or more dependent entries stemming from a higher order entry. The depth of the hierarchy may vary depending upon the particular path taken through the hierarchy.

[0033] A preferred entry form found to be well suited to the description of integrated circuits is one in which each entry specifies order, type and value for an entity at that level.

[0034] Viewed from another aspect the present invention provides a method of configuring an integrated circuit having a plurality of data processing circuit elements and a configuration memory storing configuration data describing said plurality of data processing elements, said method comprising the steps of:

[0035] (i) upon initialisation of said apparatus, reading said configuration data from said configuration memory;

[0036] (ii) determining from said configuration data configuration parameters of said integrated circuit for setting up configuration program software controlling interaction between application program software and said plurality of data processing circuit elements.

[0037] An alternative aspect of the present invention is a computer program storage medium bearing a computer program for controlling an integrated circuit to perform the above described techniques.

[0038] The human readable description of the system may also be used to control physical configuration of the system, such as controlling the layout or other physical parameters. Thus, a design flow may use the description to generate SoC (system on a chip) configuration files and the SoC tools to layout controlling data. The description data could also be passed to debug tools. By passing the SoC description to debug tools, those tools may access the physical SoC using standard mechanisms and then use the description to interpret, format and/or label returned values.

[0039] The above, and other objects, features and advantages of this invention will be apparent from the following detailed description of illustrative embodiments which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040]FIG. 1 schematically illustrates an integrated circuit including a plurality of data processing circuit elements;

[0041]FIG. 2 schematically illustrates the relationship between software elements within a data processing system;

[0042]FIG. 3 is a flow-diagram illustrating the initialisation of an integrated circuit;

[0043]FIG. 4 illustrates a hierarchical description of an integrated circuit;

[0044]FIG. 5 illustrates a design process for an integrated circuit; and

[0045] FIGS. 6 to ? illustrate further features of one example embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046]FIG. 1 illustrates an integrated circuit 2 that is of a type referred to as a system-on-a-chip device. The integrated circuit 2 includes a processor core 4, a data memory 6, a first peripheral 8, a second peripheral 10, a configuration data memory 12 and a software subroutine library memory 14. These individual data processing circuit elements are all linked by a bus 16.

[0047] The processor core 4 has associated identifying data that is included within the configuration data stored in the configuration data memory 12. The data identifying the processor core may be useful in establishing which instruction set it is operating or which capabilities the processor core 4 has. The data memory 6 has associated configuration data indicating what type of memory it is (e.g. RAM, ROM, Flash, etc), as well as its storage capacity and page size. Memory management data may also be included within the configuration data indicating whether all or parts of the data memory 6 are cacheable, bufferable, and subject to read/write restrictions.

[0048] The first peripheral 8 and the second peripheral 10 give rise to configuration data within the configuration memory 12 identifying which peripheral they are, their configuration (such as interrupt data and memory address data) as well as other information required for the integrated circuit 2 to properly use the peripheral 8, 10. It will be appreciated that there is considerable flexibility in the number and type of the peripheral devices 8, 10 that may be provided within the integrated circuit 2 and that these peripheral devices 8, 10 may come from different suppliers and design sources, such that the ability to at least partially abstract their interaction with the other portions of the system into the configuration data is highly advantageous.

[0049] The software subroutine library memory 14 is indicated as present within the configuration data and configuration data is also included indicating the location and size of a data heap within the data memory 6 that can be used by the software subroutines in the library 14.

[0050] The configuration data memory 12 is shown in FIG. 1 in the form of a read only memory. Such a read only memory can be programmed with the necessary configuration data using standard techniques. Alternatively, special purpose circuit elements, such as registers that can be read, may be provided to store the configuration data. The configuration data can be encrypted using various known encryption techniques.

[0051]FIG. 2 schematically illustrates the relationship between software elements and the hardware within the example device. At the highest level the device may execute several application programs 18, 20, 22. These application programs 18, 20, 22 interact with the operating system 24. From the point of view of the application programs 18, 20, 22, the operating system 24 provides the function of interacting and controlling the various hardware elements of the device 2. The operating system 24 may communicate directly with the device 2 for some services, but a large number of services will be provided via a basic input/output system software layer 26. This basic input/output system software layer 26 allows for the possible use of a variety of different operating systems 24 for a given design of device 2.

[0052] The initialisation program instructions 28 that control the reading of the configuration data memory 12 and the setting up of the basic input/output system software 26 are embedded within the basic input/output system software 26 itself. When the device 2 is initialised (e.g. the power is switched on or the system is reset), then the initialisation program instructions are executed to read the configuration data from the configuration data memory 12 and set up appropriate parameters for the various data processing circuit elements of the device 2 in the basic input/output system software 26.

[0053]FIG. 3 is a flow-diagram illustrating the initialisation of the device 2. At step 30, the device 2 is initialised by the switching on of power or a hardware reset. At step 32, the configuration data from the configuration data memory 12 is read under control of the initialisation program 28. At step 34, the initialisation program 28 uses the configuration data it has read to configure the basic input/output system software 26 with the variable parameters of the data processing circuit elements indicated as being present within the device 2. At step 36, the initialisation of the device 2 has been completed and processing control is passed to the operating system 24. Alternatively, the configuration of the system may not be completed until after handover of control to the operating system.

[0054]FIG. 4 illustrates a hierarchical description of an integrated circuit. In this example, an individual system-on-a-chip (SoC) system forms the highest level within the description. Beneath this highest level the components are first divided into the clock, microprocessor core, memory system, coprocessor and I/O systems. Some of the entries at this high level may not need to be further described and it is sufficient to associate type and value data with these entries in order to rigorously define the system. As an example, the core and coprocessor entries may be sufficiently defined by specifying the core as an ARM9 core and the coprocessor as a vector floating point unit. The design tools that will subsequently be responsive to this description do not need any further information regarding these particular entities other than that specified. Conversely, an entity such as the memory may be further divided into entities describing the presence or absence of an MMU (with associated parameters), a cache memory, a read only memory and a random access memory. Similarly, the I/O devices may be subdivided into individual types with their particular parameters such as address, interrupt and the like associated therewith. It will be appreciated that the description illustrated in FIG. 4 is highly simplified and that in reality many more entries and levels will be present within a typical system description with a fine level of detail regarding the configuration parameters.

[0055]FIG. 5 schematically illustrates the design process using the hierarchical syntax. The human readable description 40 is in the form of an editable text file written in accordance with the ASN.1 syntax (it will be appreciated that other description formats, such as XML, could also be used). A designer can modify elements within this editable text simply using a standard text editor to alter the description of the system to suit a particular requirement. Once the editable text 40 has been finalised, a software tool may be used to interpret this description and generate a configuration datafile 42 representing in a compact form the configuration of the system. This configuration data may then be encrypted prior to being stored within the configuration data memory 44 of a system 46 to which it relates.

[0056] There follows a further description of a software system embodying one example of the present invention:

[0057] Although illustrative embodiments of the invention have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope and spirit of the invention as defined by the appended claims. 

We claim:
 1. An integrated circuit comprising: (i) a plurality of data processing circuit elements; (ii) a configuration memory storing configuration data describing said plurality of data processing elements; and (iii) configuration logic operable upon initialisation of said apparatus to read said configuration data from said configuration memory and to determine therefrom configuration parameters of said integrated circuit for setting up configuration program software controlling interaction between application program software and said plurality of data processing circuit elements.
 2. An integrated circuit as claimed in claim 1, wherein said configuration program software is basic input output system software.
 3. An integrated circuit as claimed in claim 1, wherein said plurality of data processing circuit elements include a processor core responsive to program instructions to perform data processing operations.
 4. An integrated circuit as claimed in claim 3, wherein said configuration logic comprises said processor core operating under control of initialisation program instructions to read said configuration memory and to determine therefrom said configuration parameters.
 5. An integrated circuit as claimed in claim 3, wherein said configuration data includes data identifying said processor core.
 6. An integrated circuit as claimed in claim 1, wherein said plurality of data processing circuit elements include a data memory and said configuration data includes at least one of data identifying a type characteristic of said data memory, a capacity value of said data memory, a page size value of said data memory and data specifying access parameters for said data memory.
 7. An integrated circuit as claimed in claim 1, wherein said plurality of data processing circuit elements include a data processing peripheral circuit and said configuration data includes at least one of a memory address for said data processing peripheral and interrupt data specifying interrupts used by said peripheral.
 8. An integrated circuit as claimed in claim 1, wherein said configuration data includes data indicating whether a library of software subroutines is present and at least one of a data heap size and a data heap location.
 9. An integrated circuit as claimed in claim 1, wherein said configuration memory is a read only memory with said configuration data is fixed at manufacture of said integrated circuit.
 10. An integrated circuit as claimed in claim 1, wherein said configuration data is encrypted.
 11. A method of configuring an integrated circuit having a plurality of data processing circuit elements and a configuration memory storing configuration data describing said plurality of data processing elements, said method comprising the steps of: (i) upon initialisation of said apparatus, reading said configuration data from said configuration memory; (ii) determining from said configuration data configuration parameters of said integrated circuit for setting up configuration program software controlling interaction between application program software and said plurality of data processing circuit elements.
 12. A computer program storage medium storing a computer program for controlling an integrated circuit to perform a method as claimed in claim
 11. 13. A method of describing an integrated circuit having a plurality of circuit elements and associated configuration parameters, said method comprising the step of: (i) generating a description of said integrated circuit using a predetermined hierarchical syntax to form a human readable hierarchical description.
 14. A method as claimed in claim 13, wherein an entry within said human readable hierarchical description can have one or more dependent entries stemming therefrom at a lower level within said human readable hierarchical description.
 15. A method as claimed in claim 13, wherein said hierarchical syntax allows different portions of said human readable hierarchical description to have different hierarchical depths.
 16. A method as claimed in claim 13, wherein each entry within said human readable hierarchical description has associated variables specifying order, type and value.
 17. A method as claimed in claim 13, wherein said human readable hierarchical description is an ASN.1.
 18. A method of forming configuration data for configuring an integrated circuit as claimed in claim 11, said method of forming configuration data comprising the steps of: (i) generating a human readable hierarchical description in accordance with the method of any one of claims 13 to 17; and (ii) automatically mapping said human readable hierarchical description into said configuration data.
 19. A method as claimed in claim 18, further comprising the step of encrypting said configuration data prior to storing said configuration data in said configuration memory.
 20. A computer program storage medium storing a computer program for controlling an integrated circuit to perform a method as claimed in claim
 13. 21. A computer program storage medium storing a computer program for controlling an integrated circuit to perform a method as claimed in claim
 18. 